Paper 2023/654

Griffin: Towards Mixed Multi-Key Homomorphic Encryption

Thomas Schneider, Technical University of Darmstadt
Hossein Yalame, Technical University of Darmstadt
Michael Yonli, Technical University of Darmstadt

This paper presents Griffin, an extension of the mixed-scheme single-key homomorphic encryption framework Pegasus (Lu et al., IEEE S&P’21) to a Multi-Key Homomorphic Encryption (MKHE) scheme with applications to secure computation. MKHE is a generalized notion of Homomorphic Encryption (HE) that allows for operations on ciphertexts encrypted under different keys. However, an efficient approach to evaluate both polynomial and non-polynomial functions on encrypted data in MKHE has not yet been developed, hindering the deployment of HE to real-life applications. Griffin addresses this challenge by introducing a method for transforming between MKHE ciphertexts of different schemes. The practicality of Griffin is demonstrated through benchmarks with multiple applications, including the sorting of sixty four 45-bit fixed point numbers with a precision of 7 bits in 21 minutes, and evaluating arbitrary functions with a one-time setup communication of 1.4 GB per party and 2.34 MB per ciphertext. Moreover, Griffin could compute the maximum of two numbers in 3.2 seconds, a 2× improvement over existing MKHE approaches that rely on a single scheme.

Note: This is the full version of our research paper that has been accepted for publication at the 20th International Conference on Security and Cryptography (SECRYPT'23).

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. International Conference on Security and Cryptography (SECRYPT'23)
Secure ComputationMulti-Key Homomorphic Encryption
Contact author(s)
schneider @ encrypto cs tu-darmstadt de
yalame @ encrypto cs tu-darmstadt de
michael yonli @ stud tu-darmstadt de
2023-05-11: approved
2023-05-09: received
See all versions
Short URL
Creative Commons Attribution


      author = {Thomas Schneider and Hossein Yalame and Michael Yonli},
      title = {Griffin: Towards Mixed Multi-Key Homomorphic Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2023/654},
      year = {2023},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.